The invention relates to a medical instrument for punching out tissue.
A medical instrument of this kind is known from DE-A-103 42 002. The known medical instrument has a first cap-shaped tool arranged at a distal end of a shaft, which proximally has a circular cutting edge, with a second tool, which distally has a circular cutting edge, whereby both tools can be shifted relative to one another along the shaft, whereby the cutting edge of the second tool can be introduced into an inner cavity of the first cap-shaped tool and both cutting edges cooperate in the manner of a punch.
These medical instruments are also described as egghead or mushroom head punches.
Such medical instruments are widely used in endoscopic diagnosis, surgery and aftercare for paranasal sinuses and the front base of the skull. Their purpose for example is to open the ethmoid bone cells or the sphenoid bone cavity.
The first tool arranged at the distal end of a shaft is designed as a cap, e.g. a mushroom or an egg, so that it can be introduced into or through small body openings either naturally occurring or artificially made.
The second tool has a cutting edge which is facing the cutting edge of the first tool. The second tool is designed such that it can enter the inner cavity of the first tool at least with its cutting edge. In the process the extensive cutting edges slide closely past one another, separating any tissue in between. Both cutting edges work in the manner of a punch through their circular cutting edges. To operate the tools one is mostly fixed and the other is mobile so that both tools can be moved between an open position, in which both cutting edges are at a distance from one another, and a closed state, in which the cutting edge of the second tool is introduced into the cutting edge of the first tool.
The planes made by the circular cutting edges can run perpendicularly to the longitudinal axis of the shaft, but they can also run at an angle thereto.
The shaft itself can be straight or curved so as to be able to access sinuses in particular when employed in the ENT (ear, nose and throat) region.
During the punching or cutting edge procedure the second tool, which enters the inner cavity of the first tool, pushes or respectively pulls the separated tissue into this cavity.
Because the tools are relatively small (standard diameter variables of such a punch head are in the range of 0.1 to 0.2 inch), it is very difficult to remove the separated tissue from the inner cavity once the tools are open.
It is therefore object of the present invention to provide measures making it easier to remove tissue from the inner cavity of the first tool, i.e. from the egghead or mushroom head.